Observers from Cape Canaveral to Capitol Hill will be keenly watching SpaceX's commercial voyage to the International Space Station launching Saturday, and although officials bill the mission as a test flight, its outcome could buoy or blunt support for a private space race in human spaceflight.

Photo of the Falcon 9 rocket on the launch pad Friday. Credit: Walter Scriptunas II/Spaceflight Now

Recognizing the breadth of attention given Saturday's launch and arrival at the space station three days later, officials from NASA and SpaceX have one message: This is a test flight.

And that means to expect the unexpected.

SpaceX aims to launch its privately-built Dragon capsule Saturday aboard a Falcon 9 rocket, fly the craft to the International Space Station, and deftly approach the complex for astronauts to grab the free-flying satellite with a robot arm.

It is the first time a private company has attempted such a feat.

If successful, the flight would be a confidence boost for SpaceX and NASA, which are partners for at least 12 unmanned cargo delivery flights to the space station over the next few years.

The space agency has paid SpaceX $381 million in an agreement to help pay for the design, development, and testing of the Falcon 9 rocket and Dragon spacecraft. SpaceX has spent $1.2 billion to date, including public and private capital.

NASA and SpaceX are also jointly funding the design of a crewed version of the Dragon spacecraft to transport astronauts to the space station later this decade. SpaceX is competing with other aerospace companies for further NASA financing to support development of rockets and spacecraft for human occupants.

Among supporters of private space travel, there is concern the SpaceX test flight is inextricably tied to perception of the commercial crew program, if not its financial support from Congress.

If the flight fails to meet its objectives, it could add to a chorus of opposition. The commercial spaceflight initiative could gain more support if the mission is flawless.

"We know this has been touted as a huge mission," said Gwynne Shotwell, SpaceX's president. "We keep trying to say it's a test. Nonetheless, it's a big job. Success is not going to mean success of the commercial space industry, and failure is not going to mean failure of the commercial space industry. Certainly, it will be easier if we're able to berth with the space station."

Shotwell said the most important outcome of the Dragon test flight is to learn from it. The spacecraft's solar arrays, navigation and rendezvous sensors, and flight computer are all new.

But in the eyes of many lawmakers, space enthusiasts, and the public, the Obama administration's directive for NASA to cede low Earth orbit transportation to private industry will be also be tested during SpaceX's unmanned flight to the space station.

Sen. Bill Nelson, D-Fla., said in February the SpaceX test flight would come "at the right time" as budget decisions are made in Washington. A success, he said, would prove it is possible for commercial operators to do the work NASA has advanced since the 1960s, freeing the space agency to push farther from Earth and explore new worlds.

SpaceX has garnered more media coverage and attention from Congress than its competitors. And because SpaceX is the first commercial transportation provider to reach the launch pad, it has the distinction of making history.

"We didn't ask for that role, but we do take it very seriously," Shotwell said.

Mark Sirangelo, executive vice president at Sierra Nevada Corp., one of SpaceX's competitors in NASA's commercial crew program, said SpaceX's demonstration flight is important to the industry.

"We believe that it is important for a number of reasons," Sirangelo said. "We have satellites that are manifested to fly with SpaceX rockets in the future. Proving their cargo capacity is really good for us and the country. This is an industry that needs to be made up of multiple providers. We wish them well and I hope they are successful."

SpaceX, Sierra Nevada and other companies are waiting with NASA to see how much funding the space agency will receive for payment to commercial space developers next year.

The White House requested $830 million for the commercial crew program in fiscal year 2013, which begins Oct. 1. The House and Senate appropriations committees proposed bills calling for $500 million and $525 million.

NASA officials warn such a funding level would delay the start of crew transportation services beyond 2017, the agency's current prediction.

Some lawmakers have argued NASA is shortchanging the agency's exploration efforts, which center on a mammoth heavy-lifting rocket and government-owned crew capsule, in favor of commercial programs.

In addition to appropriating less money than NASA would like, the House budget bill would direct NASA to immediately select a single provider for commercial crew transportation services. NASA officials prefer to wait to make a choice until all companies mature their designs, complete some of their testing, and offer a clearer picture of which partners have the best chance of meeting cost and schedule targets.

Elon Musk, SpaceX's founder, CEO and chief designer, said it would be a mistake for the Dragon test flight to have a bearing on the debate in Congress.

"There's no question there will be some people who put too much weight on this flight because it is explicitly a test flight, and indeed, we may not succeed in getting all the way to the space station," Musk said. "I think it would be a mistake to put too much weight on this flight."

The next Falcon 9 rocket is already at Cape Canaveral, and its Dragon payload will arrive this summer for liftoff in the fall. Another space station cargo flight could launch by the end of 2012.

"Commercial space will be fine regardless of what happens tomorrow," Shotwell said Friday. "And we'll be back."

If Saturday's flight succeeds in reaching the space station and meeting all of its test goals, the next Falcon 9 launch will fulfill the first of SpaceX's 12 operational cargo missions under a $1.6 billion contract. In the event Dragon falls short, the next vehicle would assume a role as another test flight.

"I don't think, if this mission doesn't get all the way there, that it should be taken as a verdict on commercial crew transport," Musk said. "That wouldn't be right, although there will be some people who will try to do that."